Thrust apparatuses, systems, and methods

ABSTRACT

Described herein is a thrust system for a vehicle that includes at least three electrical power controllers, at least four electrical switches each configured to receive electrical power from at least one of the at least three electrical power controllers, and at least three thrusters each configured to receive electrical power from at least one of the at least three electrical switches. The at least four electrical switches are operable to switch a supply of electrical power from any of the at least three electrical power controllers to any one of the at least three thrusters.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 14/533,934, filed Nov. 5, 2014, which is incorporated herein byreference.

FIELD

This disclosure relates generally to propulsion systems for vehicles,and more particularly to electrically-powered thrust systems forvehicles.

BACKGROUND

Some propulsion systems for vehicles include electrically-poweredthrusters. Power for the thrusters is supplied from one or twoelectrical power controllers. For space-based vehicles, the electricalpower controllers may supply power to the thrusters for station keepingand transfer of orbit operations.

SUMMARY

The subject matter of the present application has been developed inresponse to the present state of the art. Additionally, the subjectmatter has been developed in response to the increased interest inelectrically-powered thrust systems for electric satellites, which aresolely dependent on electric propulsion. For satellites with a singlepropulsion system, enhanced redundancy schemes are desirable.Accordingly, the subject matter of the present application has beendeveloped to provide propulsion apparatuses, systems, and methods thatimprove upon prior art techniques. For example, the subject matter ofthe present application, in some implementations, provides a propulsionsystem and method that increases redundancy compared to priorelectrically-powered thrust systems. More particularly, in someembodiments, described herein is a thrust system that improvesreliability by increasing redundancy, and improves the performance oftransfer of orbit operations.

According to one embodiment, a thrust system for a vehicle includes atleast three electrical power controllers, at least four electricalswitches each configured to receive electrical power from at least oneof the at least three electrical power controllers, and at least threethrusters each configured to receive electrical power from at least oneof the at least three electrical switches. The at least four electricalswitches are operable to switch a supply of electrical power from any ofthe at least three electrical power controllers to any one of the atleast three thrusters.

In some implementations of the thrust system, the switches are operableto allow electrical power from the at least three electrical powercontrollers to be concurrently supplied to the at least three thrusters.Each electrical power controller supplies power to a respective one ofthe at least three thrusters.

According to some implementations of the thrust system, one of the atleast three electrical power controllers is a redundant powercontroller. In a first mode of operation of the thrust system, a firstof the at least three electrical power controllers supplies electricalpower to a first of the at least three thrusters, a second of the atleast three electrical power controllers supplies electrical power to asecond of the at least three thrusters, and the redundant powercontroller supplies no electrical power to the first and secondthrusters. In a second mode of operation of the thrust system, one ofthe first and second electrical power controllers supplies no electricalpower to the first and second thrusters, respectively, and the redundantpower control supplies electrical power to the one of the first andsecond electrical power controllers.

In certain implementations of the thrust system, each electrical powercontroller includes a first power output and a second power output. Eachelectrical switch includes a first power input, a second power input,and at least one of a first power output and a second power output. Thefirst power output of a first of the electrical power controllers iselectrically coupled to the first power input of a first of theelectrical switches, and the second power output of the first of theelectrical power controllers is electrically coupled to the first powerinput of a second of the electrical switches. The first power output ofa second of the electrical power controllers is electrically coupled tothe first power input of a third of the electrical switches, and thesecond power output of the second of the electrical power controllers iselectrically coupled to the second power input of a fourth of theelectrical switches. The first power output of a third of the electricalpower controllers is electrically coupled to the second power input ofthe third of the electrical switches, and the second power output of thethird of the electrical power controllers is electrically coupled to thesecond power input of the second of the electrical switches.

According to one implementation of the thrust system, the first poweroutput of the second of the electrical switches is electrically coupledto the first power input of the fourth of the electrical switches. Also,the first power output of the third of the electrical switches iselectrically coupled to the second power input of the first of theelectrical switches. Additionally, the first power output of the firstof the electrical switches is electrically coupled to a first of thethrusters, and the second power output of the first of the electricalswitches is electrically coupled to a second of the thrusters. Further,the first power output of the fourth of the electrical switches iselectrically coupled to a third of the thrusters, and the second poweroutput of the fourth of the electrical switches is electrically coupledto a fourth of the thrusters.

In an implementation of the thrust system, the first of the electricalswitches is actuatable to either (i) route electrical power from thefirst power input of the first of the electrical switches to the firstpower output of the first of the electrical switches and routeelectrical power from the second power input of the first of theelectrical switches to the second power output of the first of theelectrical switches, or (ii) route electrical power from the first powerinput of the first of the electrical switches to the second power outputof the first of the electrical switches and route electrical power fromthe second power input of the first of the electrical switches to thefirst power output of the first of the electrical switches.Additionally, the second of the electrical switches is actuatable toeither (i) route electrical power from the first power input of thesecond of the electrical switches to the first power output of thesecond of the electrical switches, or (ii) route electrical power fromthe second power input of the second of the electrical switches to thefirst power output of the second of the electrical switches. Also, thethird of the electrical switches is actuatable to either (i) routeelectrical power from the first power input of the third of theelectrical switches to the first power output of the third of theelectrical switches, or (ii) route electrical power from the secondpower input of the third of the electrical switches to the first poweroutput of the third of the electrical switches. Further, the fourth ofthe electrical switches is actuatable to either (i) route electricalpower from the first power input of the fourth of the electricalswitches to the first power output of the fourth of the electricalswitches and route electrical power from the second power input of thefourth of the electrical switches to the second power output of thefourth of the electrical switches, or (ii) route electrical power fromthe first power input of the fourth of the electrical switches to thesecond power output of the fourth of the electrical switches and routeelectrical power from the second power input of the fourth of theelectrical switches to the first power output of the fourth of theelectrical switches.

In yet one implementation of the thrust system, the switches areconfigured such that the first power outputs of the first, second, andthird electrical power controllers supply power only to the first andsecond thrusters, and the second power outputs of the first, second, andthird electrical power controllers supply power only to the third andfourth thrusters.

According to some implementations, the thrust system includes fourelectrical power controllers and four thrusters. The at least fourelectrical switches can be operable to switch a supply of electricalpower from any of the four electrical power controllers to any one ofthe four thrusters. The switches can be operable to allow electricalpower from the four electrical power controllers to be concurrentlysupplied to the four thrusters, with each electrical power controllersupplying power to a respective one of the four thrusters. In animplementation, each electrical power controller includes a first poweroutput, each electrical switch includes a first power input, a secondpower input, a first power output, and a second power output, the firstpower output of a first of the electrical power controllers iselectrically coupled to the first power input of a first of theelectrical switches, the first power output of a second of theelectrical power controllers is electrically coupled to the second powerinput of the first of the electrical switches, the first power output ofa third of the electrical power controllers is electrically coupled tothe first power input of a second of the electrical switches, and thefirst power output of a fourth of the electrical power controllers iselectrically coupled to the second power input of the second of theelectrical switches.

In one implementation of the thrust system, the first power output ofthe first of the electrical switches is electrically coupled to thefirst power input of a third of the electrical switches, the secondpower output of the first of the electrical switches is electricallycoupled to the first power input of a fourth of the electrical switches,the first power output of the second of the electrical switches iselectrically coupled to the second power input of the third of theelectrical switches, the second power output of the second of theelectrical switches is electrically coupled to the second power input ofthe fourth of the electrical switches, the first power output of thethird of the electrical switches is electrically coupled to a first ofthe thrusters, and the second power output of the third of theelectrical switches is electrically coupled to a second of thethrusters, and the first power output of the fourth of the electricalswitches is electrically coupled to a third of the thrusters, and thesecond power output of the fourth of the electrical switches iselectrically coupled to a fourth of the thrusters.

According to an implementation of the thrust system, the first of theelectrical switches is actuatable to either (i) route electrical powerfrom the first power input of the first of the electrical switches tothe first power output of the first of the electrical switches and routeelectrical power from the second power input of the first of theelectrical switches to the second power output of the first of theelectrical switches, or (ii) route electrical power from the first powerinput of the first of the electrical switches to the second power outputof the first of the electrical switches and route electrical power fromthe second power input of the first of the electrical switches to thefirst power output of the first of the electrical switches. Further, thesecond of the electrical switches is actuatable to either (i) routeelectrical power from the first power input of the second of theelectrical switches to the first power output of the second of theelectrical switches and route electrical power from the second powerinput of the second of the electrical switches to the second poweroutput of the second of the electrical switches, or (ii) routeelectrical power from the first power input of the second of theelectrical switches to the second power output of the second of theelectrical switches and route electrical power from the second powerinput of the second of the electrical switches to the first power outputof the second of the electrical switches. Also, the third of theelectrical switches is actuatable to either (i) route electrical powerfrom the first power input of the third of the electrical switches tothe first power output of the third of the electrical switches and routeelectrical power from the second power input of the third of theelectrical switches to the second power output of the third of theelectrical switches, or (ii) route electrical power from the first powerinput of the third of the electrical switches to the second power outputof the third of the electrical switches and route electrical power fromthe second power input of the third of the electrical switches to thefirst power output of the third of the electrical switches.Additionally, the fourth of the electrical switches is actuatable toeither (i) route electrical power from the first power input of thefourth of the electrical switches to the first power output of thefourth of the electrical switches and route electrical power from thesecond power input of the fourth of the electrical switches to thesecond power output of the fourth of the electrical switches, or (ii)route electrical power from the first power input of the fourth of theelectrical switches to the second power output of the fourth of theelectrical switches and route electrical power from the second powerinput of the fourth of the electrical switches to the first power outputof the fourth of the electrical switches.

In some implementations of the thrust system, each of the threethrusters is an ion propulsion thruster. Each of the three thrusters canbe enabled for maximum thrust output. The at least four electricalswitches can be configured such that each of the at least threeelectrical power controllers supplies electrical power to only one ofthe at least three thrusters at a time.

According to another embodiment, a thrust system for a vehicle includesat least three electrical power controllers, at least four electricalswitches in power receiving communication with at least one of theelectrical power controllers, and at least four thrusters each in powerreceiving communication with one of the electrical switches. The thrustsystem also includes a system controller that is operably coupled to theelectrical switches and thrusters to control electrical power supplyfrom the electrical power controllers to the thrusters, wherein in afirst mode the system controller operates the electrical switches andthrusters to nonconcurrently supply power to each of the four thrustersfrom less than three electrical power controllers, and in a second modethe system controller operates the electrical switches and thrusters toconcurrently supply power to each of three of the four thrusters from arespective one of the three electrical power controllers. As definedherein, supplying power to the thrusters from controllers in thisembodiment, and relative implementations, means the thrusters areconsuming electrical power received from the controllers to generatethrust.

According to some implementations of the thrust system, in a third modethe system controller operates the electrical switches and thrusters tononconcurrently supply power to each of the four thrusters from lessthan three electrical power controllers, wherein one of the electricalpower controllers supplying power to the thrusters in the third modedoes not supply power to the thrusters in the first mode.

In one implementation of the thrust system, the vehicle includes asatellite, and the system further includes the satellite.

According to yet another embodiment, a thrust system for a vehicleincludes at least four electrical power controllers, at least fourelectrical switches in power receiving communication with at least oneof the electrical power controllers, and at least four thrusters each inpower receiving communication with one of the electrical switches. Thethrust system also includes a system controller operably coupled to theelectrical switches and thrusters to control electrical power supplyfrom the electrical power controllers to the thrusters, wherein in afirst mode the system controller operates the electrical switches andthrusters to nonconcurrently supply power to each of the four thrustersfrom less than four electrical power controllers, and in a second modethe system controller operates the electrical switches and thrusters toconcurrently supply power to each of the four thrusters from arespective one of the four electrical power controllers.

According to one implementation of the thrust system, in a third modethe system controller operates the electrical switches and thrusters tononconcurrently supply power to each of the four thrusters from adedicated one of each of the four electrical power controllers.

In yet another embodiment, a method for providing thrust for a vehicleincludes supplying electrical power from at least a first of at leastthree electrical power controllers, and routing electrical power fromthe at least first of the at least three electrical power controllers toany of at least four thrusters via at least three electrical switches.

In some implementations of the method, at least a second of the threeelectrical power controllers does not supply electrical power, and themethod further includes stopping the supply of electrical power from theat least first of the three electrical power controllers, supplyingelectrical power from the at least second of the at least threeelectrical power controllers, and routing electrical power from the atleast second of the at least three electrical power controllers to anyof the at least four thrusters via at least three electrical switches.

According to certain implementations, the method further includessupplying electrical power from each of the at least three electricalpower controllers, and concurrently routing electrical power from the atleast three electrical power controllers to a respective one of each ofthree of the at least four thrusters. The vehicle can be a satellite.Electrical power from each of the at least three electrical powercontrollers can be supplied and electrical power from the at least threeelectrical power controllers can be concurrently routed to a respectiveone of each of three of the at least four thrusters to concurrentlygenerate thrust during a transfer orbit operation of the satellite. Asdefined in this embodiment, routing electrical power to the thrustersmeans consuming electrical power by the thrusters to generate thrust.

The described features, structures, advantages, and/or characteristicsof the subject matter of the present disclosure may be combined in anysuitable manner in one or more embodiments and/or implementations. Inthe following description, numerous specific details are provided toimpart a thorough understanding of embodiments of the subject matter ofthe present disclosure. One skilled in the relevant art will recognizethat the subject matter of the present disclosure may be practicedwithout one or more of the specific features, details, components,materials, and/or methods of a particular embodiment or implementation.In other instances, additional features and advantages may be recognizedin certain embodiments and/or implementations that may not be present inall embodiments or implementations. Further, in some instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the subject matter ofthe present disclosure. The features and advantages of the subjectmatter of the present disclosure will become more fully apparent fromthe following description and appended claims, or may be learned by thepractice of the subject matter as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the subject matter may be more readilyunderstood, a more particular description of the subject matter brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the subject matter and arenot therefore to be considered to be limiting of its scope, the subjectmatter will be described and explained with additional specificity anddetail through the use of the drawings, in which:

FIG. 1 is a schematic block diagram of a vehicle with a thrust systemaccording to one embodiment;

FIG. 2 is a schematic block diagram of a thrust system with a first typeof switch according to one embodiment;

FIG. 3 is a schematic block diagram of a thrust system with a secondtype of switch according to one embodiment;

FIG. 4 is a schematic block diagram of a thrust system in a firstconfiguration according to one embodiment;

FIG. 5 is a schematic block diagram of the thrust system of FIG. 4 in asecond configuration according to one embodiment;

FIG. 6 is a schematic block diagram of the thrust system of FIG. 4 in athird configuration according to one embodiment;

FIG. 7 is a schematic block diagram of a thrust system in a firstconfiguration according to another embodiment;

FIG. 8 is a schematic block diagram of the thrust system of FIG. 7 in asecond configuration according to one embodiment; and

FIG. 9 is a schematic flow diagram of a method for providing thrustaccording to one embodiment.

DETAILED DESCRIPTION

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment. Similarly, the use of theterm “implementation” means an implementation having a particularfeature, structure, or characteristic described in connection with oneor more embodiments of the present disclosure, however, absent anexpress correlation to indicate otherwise, an implementation may beassociated with one or more embodiments.

Referring to FIG. 1, one embodiment of a vehicle 10 includes a thrustsystem 100. The vehicle 10 can be any of various vehicles propelled bythrust, such as an aircraft, spacecraft, automobile, watercraft, and thelike. In one embodiment, the vehicle 10 is a satellite propelled throughspace by the thrust system 100. The thrust system 100 includes powercontrollers 110, switches 120, and thrusters 130. Operation of the powercontrollers 110 and switches 120 is controlled by a system controller140. Generally, the system controller 140 commands the power controllers110 to supply electrical power to the switches 120, commands theswitches to route the received electrical power from the powercontrollers to the thrusters 130, and commands the thrusters 130 toswitch on to consume the electrical power and provide thrust. The systemcontroller 140 may control the power controllers 110, switches 120, andthrusters 130 according to one or more modes as will be described inmore detail below.

As shown in FIG. 2, one embodiment of a thrust system 200 includes firstand second power inputs 220, 230, respectively, a switch 240, and firstand second thrust outputs 250, 260, respectively. Generally, the thrustsystem 200 is configured to selectively supply electrical power from oneor more electrical power controllers to one or more thrusters, or otherswitches, via the switch 240. The first power input 220 representselectrical power supplied by a first electrical power controller, andthe second power input 230 represents electrical power supplied by asecond electrical power controller. Similarly, the first thrust output250 represents electrical power transmitted to a first thruster, and thesecond thrust output 260 represents electrical power transmitted to asecond thruster.

The operation of the switch 240 is shown generally. In one embodiment,the switch 240 is selectively operable, and switchable between, twomodes of operation. In a first, or normal, mode of operation, the switch240 outputs the first power input 220 as the first thrust output 250 viaa first electrical circuit 270A defined by the switch, and separatelyoutputs the second power input 230 as the second thrust output 260 via aseparate second electrical circuit 270B defined by the switch. Incontrast, in the second, or cross-strapped, mode of operation, theswitch 240 outputs the first power input 220 as the second thrust output260 via a third electrical circuit 280A defined by the switch, andseparately outputs the second power input 230 as the first thrust output250 via a separate fourth electrical circuit 280B defined by the switch.

Referring to FIG. 3, according to another embodiment, a thrust system210 includes a switch 290. Like the thrust system 200 of FIG. 2, thethrust system 210 of FIG. 3 includes first and second power inputs 220,230, respectively. However, the thrust system 210 includes only a firstthrust output 250, and does not include a second thrust output 260.Generally, the thrust system 210 is configured to selectively supplyelectrical power from one or more electrical power controllers to onethruster, or one other switch, via the switch 290. In other words, theswitch 290 includes two power inputs and one power output. In oneimplementation, the switch 290 includes a second power output port thatis capped to prevent the port from transmitting power.

The operation of the switch 290 is shown generally. In one embodiment,the switch 290 is selectively operable, and switchable between, twomodes of operation. In a first, or normal, mode of operation, the switch290 outputs the first power input 220 as the first thrust output 250 viathe first electrical circuit 270A defined by the switch. In contrast, inthe second, or cross-strapped, mode of operation, the switch 290 outputsthe second power input 230 as the first thrust output 250 via the fourthelectrical circuit 280B defined by the switch.

According to some implementations, the switches 240, 290 may beselectively switched between the first and second modes based on theinoperability of one or more of the first and second power controllersand/or inoperability of one or more of the first and second thrusters.For example, should one thruster become disabled, and power is desirablysupplied from the first power controller for any of various reasons, theswitches 240, 290 can be switched from the first mode to the secondmode. Similarly, in another example, should operation of the firstthruster be desired, and the first power controller become disabled, theswitches 240, 290 can be switched from the first mode to the secondmode.

The switches 240, 290 can be any of various physical switches forrouting electrical power between electrical power connectors andthrusters. As will be described in more detail below, the voltage andcurrent of the electrical power routed by the switches 240, 290 are highand sufficient to power an electrically-powered thruster for a vehicle.Accordingly, the voltage and current of the electrical power routed bythe switch 240, 290 are significantly higher than the voltages andcurrents of electrical communications routed through computer hardwareswitches. For example, in one implementation, the current of theelectrical power routed by the switches 240, 290 is on the order of tensand hundreds of amps (e.g., about 30 amps), while the current ofelectrical communications in computer environments is on the order oftenths and hundredths of amps. Similarly, according to someimplementations, the voltage of electrical power routed by the switches240, 290 can be up to 1,000 volts, and even higher is some cases.Therefore, the switches 240, 290 are not the same as a computer switchfor routing electrical communication signals within a computingenvironment.

According to some embodiments, the switches 240, 290 are rotaryswitches, such as described in U.S. patent application Ser. No.13/683,688, filed Nov. 21, 2012, and Ser. No. 14/258,954, filed Apr. 22,2014, which are incorporated herein by reference. Generally, a rotaryswitch includes a shaft assembly that is rotatable to switch between thefirst and second modes of operation.

Referring now to FIG. 4, according to one embodiment, a thrust system300 includes first, second, and third power controllers 310A-C, firstand second switches 240A-B, third and fourth switches 290A-B, and first,second, third, and fourth thrusters 350A-D, respectively. The first,second, and third power controllers 310A-C are respectively electricallyconnected to the first and second switches 240A-B, and third and fourthswitches 290A-B, by electrical lines as indicated by solid directionallines extending between these components in FIG. 4. Similarly, the firstand second switches 240A-B, and third and fourth switches 290A-B, arerespectively electrically connected to the first, second, third, andfourth thrusters 350A-D by electrical lines as indicated by soliddirectional lines extending between these components in FIG. 4.

As used in all FIGS. 4-8, the solid directional lines extending betweencomponents represent electrical lines and the direction of transmissionof electrical power through the electrical lines. The electrical linescan be a single or multiple electrical conduits/circuits in someimplementations. According to one implementation, each electrical linebetween components includes multiple circuits (e.g., 9 circuits) thatare switches simultaneously to transmit power through the electricalline. Generally, the electrical lines between the components transmitelectrical power between the components.

The electrical lines are electrically coupled to each component via oneor more input and/or output terminals. The terminals facilitate theelectrical connection between the components and an electrical line, andthe transmission of electrical power between the components. Forexample, the first power controller 310A includes a first outputterminal 320A and a second output terminal 322A, the second powercontroller 310B includes a first output terminal 320B and a secondoutput terminal 322B, and the third power controller 310C includes afirst output terminal 320C and a second output terminal 322C. Also as anexample, the first switch 240A includes first input terminal 340A,second input terminal 342A, first output terminal 344A, and secondoutput terminal 346A, the second switch 240B includes first inputterminal 340B, second input terminal 342B, first output terminal 344B,and second output terminal 346B, the third switch 290A includes firstinput terminal 340C, second input terminal 342C, and first outputterminal 344C, and the fourth switch 290B includes first input terminal340D, second input terminal 342D, and first output terminal 344D. Also,the first thruster 350A includes a first input terminal 352A, the secondthruster 350B includes a first input terminal 352B, the third thruster350C includes a first input terminal 352C, and the fourth thruster 350Dincludes a first input terminal 352D.

Regarding the interconnection between the power controllers and theswitches, although other configurations are possible in view of thepresent disclosure, in the illustrated configuration of the thrustsystem 300, the first output terminal 320A of the first power controller310A is electrically connected directly to the first input terminal 340Aof the first switch 240A, and the second output terminal 322A of thefirst power controller is electrically connected directly to the firstinput terminal 340C of the third switch 290A. Additionally, the firstoutput terminal 320B of the second power controller 310B is electricallyconnected directly to the first input terminal 340D of the fourth switch290B, and the second output terminal 322B of the second power controlleris electrically connected directly to the second input terminal 342B ofthe second switch 240B. Furthermore, the first output terminal 320C ofthe third power controller 310C is electrically connected directly tothe second input terminal 342D of the fourth switch 290B, and the secondoutput terminal 322C of the third power controller is electricallyconnected directly to the second input terminal 342C of the third switch290A.

Regarding the interconnection between the switches and the thrusters,although other configurations are possible in view of the presentdisclosure, in the illustrated configuration of the thrust system 300,the first output terminal 344A of the first switch 240A is electricallyconnected directly to the input terminal 352A of the first thruster350A, and the second output terminal 346A of the first switch iselectrically connected directly to the input terminal 352B of the secondthruster 350B. Also, the first output terminal 344B of the second switch240B is electrically connected directly to the input terminal 352C ofthe third thruster 350C, and the second output terminal 346B of thesecond switch is electrically connected directly to the input terminal352D of the fourth thruster 350D. Furthermore, the first output terminal344C of the third switch 290A is electrically connected directly to thefirst input terminal 340B of the second switch 240B, and the firstoutput terminal 344D of the fourth switch 290B is electrically connecteddirectly to the second input terminal 342A of the first switch 240A.

In some implementations, each first, second, and third power controller310A-C is coupled to or includes a power source, such as a battery(e.g., a solar-powered battery). Each power controller 310A-C controlsthe supply of power from a power source to the output terminals of therespective controller. Further, when powered on or “hot,” each powercontroller 310A-C is configured to supply electrical power to its outputterminals concurrently. In other words, when on, each power controller310A-C supplies electrical power to its output terminals at the sametime, such that both output terminals of a single power controller areconsidered hot at the same time. However, a single thruster consumeselectrical power from only one of the output terminals of a powercontroller at a time depending on the selective operation of thethruster. In some implementations, a system controller controls theoperation of the switches and thrusters to determine which thrustersreceive power from which output terminals of which power controller. Thefirst, second, and third power controllers 310A-C can be operated andactivated independently of each other via a system controller so thateach power controller can be considered redundant relative to the otherpower controllers.

The first and second switches 240A, 240B of the thrust system 300 areconfigured similarly to switch 240 of FIG. 2. The third and fourthswitches 290A, 290B of the thrust system 300 are configured similarly toswitch 290 of FIG. 3.

Each first, second, third, and fourth thruster 350A-D can be any ofvarious thrusters known in the art. For example, according to oneimplementation, each thruster 350A-D includes an ion propulsion systemknown in the art, such as ion propulsion systems that use griddedthrusters, ion propulsion systems that use Hall effect thrusters, andthe like. For example, according to some implementations, each of thethrusters 350A-D can be a xenon (or other ionizable gas) ion propulsionsystem for providing thrust for station keeping and transfer of orbit ofsatellites. Generally, the first, second, third, and fourth thrusters350A-D utilize electrical power from one or all of the first, second,and third power controllers 310A-C to generate propulsion by heating andaccelerating charged ions from the gas. In some implementations, thethrusters 350A-D each includes an ion extraction assembly, a housingwhich forms an ionization chamber, a discharge electron source and anelectrode system which are positioned within the chamber, a magneticfield generator, which is also positioned within the chamber, and aneutralizer positioned adjacent the ion extraction assembly.

In a basic operation of an ion propulsion system, the ionizable gas issupplied to the chamber via a valve and primary electrons are injectedinto the gas from the electron source. A discharge voltage applied tothe electrode system accelerates these electrons into collisions withgas atoms to generate a plasma. The magnetic field generator typicallyincludes annular permanent magnets and is configured to develop magneticflux lines proximate to the housing. The magnetic flux lines directelectrons along extended paths, and thus enhance the generation of theplasma. The ion extraction assembly has a screen grid, an acceleratorgrid, and a decelerator grid. Electrical power from one or more of thepower controllers 320A-C is applied to the grids to cause the ionextraction assembly to extract an ion beam from the plasma andaccelerate it away from the thruster. The ion beam generates a forceupon the ion thruster and spacecraft to which it is attached. Finally,the neutralizer injects an electron stream into the proximity of the ionbeam to offset potential charge-depleting effects of the ion beam. Thefirst, second, third, and fourth thrusters 350A-D can be operatedindependently of each other so that each thruster can be consideredredundant relative to the other thrusters.

Although the thrusters 350A-D of the illustrated embodiment aredescribed as ion propulsion systems, in other embodiments, other typesof electrical propulsion systems, or even chemical propulsion systemscan be used. Similarly, although in the illustrated embodiments, theelectrical devices receiving electrical power from the power controllersare thrusters, in other embodiments, the electrical devices can be anyof various other electrical devices. Moreover, although the system ofthe illustrated embodiment includes three power controllers, fourswitches, and four thrusters, in other embodiments, the system caninclude more than three power controllers, more than four switches,and/or more than four thrusters.

The thrust system 300, as shown in FIG. 4, is configured in a firstoperational mode. In the first operational mode, each of the first andsecond switches 240A-B and third and fourth switches 290A-B areconfigured in a normal mode of operation. In the normal mode ofoperation, as indicated by dashed directional lines, the first inputterminals 340A-D of the first, second, third, and fourth switches areelectrically connected to the first output terminals 344A-D of thefirst, second, third, and fourth switches 240A, 240B, 290A, 290B,respectively, and the second input terminals 342A-B of the first andsecond switches are electrically connected to the second outputterminals 346A-B of the first and second switches, respectively.

With the thrust system 300 configured in the first operational mode, asshown using directional lines, electrical power from the first outputterminal 320A of the first power controller 310A is routed to the firstthruster 350A to power the first thruster 350A, electrical power fromthe first output terminal 320B of the second power controller 310B isrouted to the second thruster 350B, electrical power from the secondoutput terminal 322A of the first power controller is routed to thethird thruster 350C, and electrical power from the second outputterminal 322B of the second power controller is routed to the fourththruster 350D. Furthermore, in the first operational mode, the first andsecond output terminals 320C, 322C of the third power controller 310Care electrically isolated from the thrusters. In this manner, the thirdpower controller 310C can be considered an inactive, or redundant,controller because the third power controller is not used to supplypower to any of the thrusters.

As shown in FIG. 5, the thrust system 300 can be configured in a secondoperational mode. In the second operational mode, one or both of thefirst and second switches 240A-B are configured in a cross-strapped modeof operation. As indicated by dashed directional lines, in thecross-strapped mode of operation, the first input terminals 340A-B ofthe first and second switches 240A-B are electrically connected to thesecond output terminals 346A-B of the first and second switches,respectively, and the second input terminals 342A-B of the first andsecond switches are electrically connected to the first output terminals344A-B of the first and second switches, respectively.

With the thrust system 300 configured in the second operational mode,electrical power from the first output terminal 320A of the first powercontroller 310A is routed to the second thruster 350B to power thesecond thruster, electrical power from the first output terminal 320B ofthe second power controller 310B is routed to the first thruster 350A,electrical power from the second output terminal 322A of the first powercontroller is routed to the fourth thruster 350D, and electrical powerfrom the second output terminal 322B of the second power controller isrouted to the third thruster 350C. Although both of the first and secondswitches 240A-B are shown in the cross-strapped mode of operation, insome implementations, only one of the first and second switches is inthe cross-strapped mode of operation.

In the first and second operational modes, the thrust system 300 iscapable of powering no more than two of the four thrusters 350A-D at atime. Should it be desirable to power three thrusters 350A-D at a time,such as for the transfer of orbit of a satellite, or should one or bothof the first and second power controllers 310A-B become inoperable, orshould it be desirable to reduce usage of the first and/or second powercontrollers, the thrust system 300 can be configured into a thirdoperational mode as shown in FIG. 6. In the third operational mode, oneor both of the third and fourth switches 290A-B are configured in across-strapped mode of operation. As indicated by dashed directionallines, in the cross-strapped mode of operation, the second inputterminals 342C-D of the third and fourth switches 290A-B areelectrically connected to the first output terminals 344C-D of the thirdand fourth switches, respectively.

With the thrust system 300 configured in the third operational mode,electrical power from the first output terminal 320C of the third powercontroller 310C is routed to the fourth switch 290B, and from the fourthswitch routed to either the first or second thruster 350A-B depending onthe configuration of the first switch 240A. Similarly, in the thirdoperational mode, electrical power from the second output terminal 322Cof the third power controller 310C is routed to the third switch 290A,and from the third switch routed to either the third or fourth thruster350C-D depending on the configuration of the second switch 240B.Although both of the third and fourth switches 290A-B are shown in thecross-strapped mode of operation, in some implementations, only one ofthe third and fourth switches is in the cross-strapped mode ofoperation.

Based on the foregoing, the thrust system 300 can be switched betweenfirst, second, and third operational modes depending on the conditionand/or desired performance of the thrust system. For example, the thrustsystem 300 can be operated in either the first or second operationalmodes when providing thrust for station keeping operations of asatellite is needed. As described above, in the first or secondoperational modes, one or two of the thrusters can be powered at a timeto provide the necessary thrust for station keeping operations. Then,when a transfer of orbit operation is necessary, the thrust system 300can be switched to the third operational mode, which allows up to threeof the thrusters to be powered concurrently. With more than twothrusters providing thrust concurrently, transfer of orbit operationscan be performed quicker and more efficiently than with two or fewerthrusters. Additionally, should one or both of the first and secondpower controllers 310A-B become inoperable (e.g., malfunction orexperience a performance drop), the thrust system 300 can be operated inthe third operational mode to allow the third power controller 310C toeffectively replace the inoperable power controller(s).

In some implementations, the thrusters of the thrust system 300 aregrouped together to form separate groups associated with particularlocations on a vehicle 10. For example, the first and second thrusters350A-B can be grouped together at a specific location, such as a northside, of the vehicle 10. In contrast, the third and fourth thrusters350C-D can be grouped together at another location, such as a southside, of the vehicle 10. For simplifying the control process, the thrustsystem 300 is configured such that, regardless of the mode of operationof the switches, electrical power from any of the first output terminals320A-C of the power controllers 310A-C is always routed to one or bothof the thrusters in a designated group of thrusters, such as, e.g., thefirst and second thrusters 350A-B on a north side of the vehicle 10, andelectrical power from any of the second output terminals 322A-C of thepower controllers is always routed to one or both of the thrusters in adifferent designated group of thrusters, such as, e.g., the third andfourth thrusters 350C-D on a south side of the vehicle 10.

Referring now to FIG. 7, according to one embodiment, a thrust system400 similar to the thrust system 300 is shown. The thrust system 400includes some features similar to the features of the thrust system 300.For example, the thrust system 400 includes first, second, and thirdpower controllers 310A-C, first and second switches 240A-B, and first,second, third, and fourth thrusters 350A-D. However, unlike the thrustsystem 300, the thrust system 400 includes a fourth power controller310D. Additionally, instead of third and fourth switches 290A-B, thethrust system 400 includes third and fourth switches 240C-D. The thirdand fourth switches 240C-D are the same as the first and second switches240A-B in that the third and fourth switches have two output terminals344A-B, 346A-B, respectively, instead of a single output terminal. Inother words, the third and fourth switches 240C, 240D of the thrustsystem 300 are configured similarly to switch 240 of FIG. 2.

The first, second, third, and fourth power controllers 310A-D arerespectively electrically connected to the third and fourth switches240C-D by electrical lines as indicated by solid directional linesextending between these components. Similarly, the third and fourthswitches 240C-D are respectively electrically connected to the first andsecond switches 240A-B by electrical lines as indicated by solid linesextending between these components. The first and second switches 240A-Bare respectively electrically connected to the first, second, third, andfourth thrusters 350A-D by electrical lines as indicated by soliddirectional lines extending between these components. As with the thrustsystem 300, the electrical lines of the thrust system 400 areelectrically coupled to each component via one or more input and/oroutput terminals.

Regarding the interconnection between the power controllers and theswitches, although other configurations are possible in view of thepresent disclosure, in the illustrated configuration of the thrustsystem 400, the first output terminal 320A of the first power controller310A is electrically connected directly to the first input terminal 340Cof the third switch 240C, and the second output terminal 322A of thefirst power controller is capped or inactive (e.g., not electricallyconnected to any switch or thruster). Additionally, the first outputterminal 320B of the second power controller 310B is electricallyconnected directly to the second input terminal 342D of the fourthswitch 240D, and the second output terminal 322B of the second powercontroller is inactive. Furthermore, the first output terminal 320C ofthe third power controller 310C is electrically connected directly tothe second input terminal 342C of the third switch 240C, and the secondoutput terminal 322C of the third power controller is inactive.Similarly, the first output terminal 320D of the fourth power controller310D is electrically connected directly to the first input terminal 340Dof the fourth switch 240D, and the second output terminal 322D of thefourth power controller is inactive. Accordingly, in the illustratedembodiment, each of the second output terminals of the power controllersis inactive such that each power controller provides a single activeoutput terminal for supplying electrical power. In an alternativeembodiment, at least one or all of the power controllers may utilize thesecond output terminal as the single active output terminal and renderinactive the first output terminal.

Regarding the interconnection between the switches and the thrusters,although other configurations are possible in view of the presentdisclosure, in the illustrated configuration of the thrust system 400,the first output terminal 344C of the third switch 240C is electricallyconnected directly to the first input terminal 340A of the first switch240A, and the second output terminal 346C of the third switch 240C iselectrically connected directly to the first input terminal 340B of thesecond switch 240B. In contrast, the first output terminal 344D of thefourth switch 240D is electrically connected directly to the secondinput terminal 342A of the first switch 240A, and the second outputterminal 346D of the fourth switch 240D is electrically connecteddirectly to the second input terminal 342B of the second switch 240B.Like the thrust system 300, the first output terminal 344A of the firstswitch 240A is electrically connected directly to the input terminal352A of the first thruster 350A, and the second output terminal 346A ofthe first switch is electrically connected directly to the inputterminal 352B of the second thruster 350B. Also, the first outputterminal 344B of the second switch 240B is electrically connecteddirectly to the input terminal 352C of the third thruster 350C, and thesecond output terminal 346B of the second switch is electricallyconnected directly to the input terminal 352D of the fourth thruster350D.

The thrust system 400, as shown in FIG. 7, is configured in a firstoperational mode. In the first operational mode, each of the first,second, third, and fourth switches 240A-D are configured in a normalmode of operation. In the normal mode of operation, as indicated bydashed directional lines, the first input terminals 340A-D of theswitches 240A-D are electrically connected to the first output terminals344A-D of the switches, respectively, and the second input terminals342A-D of the switches are electrically connected to the second outputterminals 346A-D of the switches, respectively.

With the thrust system 400 configured in the first operational mode, asshown using directional lines, electrical power from the first outputterminal 320A of the first power controller 310A is routed to the firstthruster 350A to power the first thruster 350A, electrical power fromthe first output terminal 320B of the second power controller 310B isrouted to the fourth thruster 350D, electrical power from the firstoutput terminal 320C of the third power controller 310C is routed to thethird thruster 350C, and electrical power from the first output terminal320D of the fourth power controller is routed to the second thruster350B.

As shown in FIG. 8, the thrust system 400 can be configured in a secondoperational mode. In the second operational mode, at least one of thefirst, second, third, and fourth switches 240A-D are configured in across-strapped mode of operation. As indicated by dashed directionallines, in the cross-strapped mode of operation, the first inputterminals 340A-D of the switches 240A-D are electrically connected tothe second output terminals 346A-D of the switches, respectively, andthe second input terminals 342A-D of the switches are electricallyconnected to the first output terminals 344A-D of the switches,respectively.

With the thrust system 400 configured in the second operational mode andall the switches in the cross-strapped mode of operation, electricalpower from the first output terminal 320A of the first power controller310A is routed to the fourth thruster 350D to power the fourth thruster,electrical power from the first output terminal 320B of the second powercontroller 310B is routed to the first thruster 350A, electrical powerfrom the first output terminal 320C of the third power controller 310Cis routed to the second thruster 350B, and electrical power from thefirst output terminal 320D of the fourth power controller 310D is routedto the third thruster 350C.

Although all of the switches 240A-D are shown in the cross-strapped modeof operation in FIG. 8, in some implementations, in the secondoperational mode of the thrust system 400, less than all of the switchesare in the cross-strapped mode of operation. Generally, any one or moreof the switches 240A-D can be operated in the cross-strapped mode ofoperation such that any one of the power controllers 310A-D can supplypower to any one of the thrusters 350A-D.

Based on the foregoing, the thrust system 400 can be switched betweenfirst and second operational modes depending on the condition and/ordesired performance of the thrust system. For example, the thrust system400 can be operated in either the first or second operational modes whenproviding thrust for station keeping operations of a satellite isneeded. As described above, in the first or second operational modes,any of the thrusters can be powered one, two, or even three at a time byany one, two, or three of the power controllers to provide the necessarythrust for station keeping operations. Then, when a transfer of orbitoperation is necessary, each of the four power controllers of the thrustsystem 400 is concurrently operated to supply power to a respective oneof the four thrusters, which allows all four of the thrusters to bepowered concurrently. With all four thrusters providing thrustconcurrently, transfer of orbit operations can be performed quicker andmore efficiently than with three or fewer thrusters. Additionally,should one, two, or three of the four power controllers of the system400 become inoperable, any operable power controller(s) remaining can beused to supply power to any of the thrusters to effectively replace theinoperable power controller(s).

According to one embodiment, two of the four power controllers of thethrust system 400 can function as cold spares, while the other two powercontrollers function as the hot power controllers. In such anembodiment, the two hot power controllers supply the power for all thethrusters via frequent cycling of the switches. The cold spares remaininactive unless a failure of one or both of the hot power controllersrequires one or both of the cold spares to be activated to replace afailed power controller, or unless a transfer of orbit operation demandsone or more of the cold spares be activated for concurrently poweringmore than two thrusters. Alternatively, if less frequent cycling of theswitches is desirable, in one embodiment, each of the four powercontrollers is a hot power controller that supplies power to a dedicatedone of the four thrusters. Accordingly, according to someimplementations, the present system allows for the use of cold spars andtime sharing flexibility to improve reliability. Additionally, thesystem is configured to facilitate extended periods of non-use (e.g., upto 20 years) commonly associated with satellite applications. Also, thesimplicity of the command structure for powering the thrusters reducesre-learning time following an extended period of non-use, which reduceserrors from infrequent operation or untrained operators.

Referring to FIG. 9, one embodiment of a method 500 for providing thrustfor a vehicle includes providing at least three power controllers, atleast three electrical switches, and at least four thrusters at 510. Themethod 500 further includes supplying electrical power from at least afirst of the three electrical power controllers at 520. Supplyingelectrical power may include providing electrical power to a poweroutput terminal of the first electrical power controller. The method 500includes routing electrical power from the first electrical powercontroller to any of the four thrusters via the three electricalswitches at 530. In response to receiving electrical power, thethrusters convert the electrical power into thrust for propelling thevehicle. At 540, the method 500 determines if a redundant electricalpower controller is needed. As an example, a redundant electrical powercontroller may be needed if an electrical power controller supplyingelectrical power becomes inoperable. If a redundant electrical powercontroller is needed at 540, the method 500 proceeds to stop the supplyof electrical power from the first electrical power controller (if thesupply of electrical power has not already been stopped), supplyelectrical power from a second of the electrical power controllers thatpreviously was not supplying electrical power, and route electricalpower from the second electrical power controller to any of the fourthrusters via the three electrical switches at 550. Step 550 may also,or alternatively, include rerouting a supply of electrical power from anoperable electrical power controller to a thruster that was previouslyreceiving electrical power from a now inoperable electrical powercontroller. If a redundant electrical power controller is not needed at540, the method 500 proceeds to step 560.

At 560, the method 500 determines whether a transfer of orbit operationis needed. If a transfer of orbit operation is needed at 560, then themethod 500 supplies electrical power from each of the three electricalpower controllers, and concurrently routes the electrical power from thethree electrical power controllers to respective thrusters of the fourthrusters at 570 and ends. Concurrently supplying electrical power tothree or more thrusters results in three or more thrusters concurrentlyproviding thrust, which increases the overall thrust available for thetransfer or orbit operation compared to two or fewer thrusters. If notransfer of orbit operation is needed at 560, then the method 500 ends.

In the above description, certain terms may be used such as “up,”“down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,”“over,” “under” and the like. These terms are used, where applicable, toprovide some clarity of description when dealing with relativerelationships. But, these terms are not intended to imply absoluterelationships, positions, and/or orientations. For example, with respectto an object, an “upper” surface can become a “lower” surface simply byturning the object over. Nevertheless, it is still the same object.Further, the terms “including,” “comprising,” “having,” and variationsthereof mean “including but not limited to” unless expressly specifiedotherwise. An enumerated listing of items does not imply that any or allof the items are mutually exclusive and/or mutually inclusive, unlessexpressly specified otherwise. The terms “a,” “an,” and “the” also referto “one or more” unless expressly specified otherwise. Further, the term“plurality” can be defined as “at least two.”

Additionally, instances in this specification where one element is“coupled” to another element can include direct and indirect coupling.Direct coupling can be defined as one element coupled to and in somecontact with another element. Indirect coupling can be defined ascoupling between two elements not in direct contact with each other, buthaving one or more additional elements between the coupled elements.Further, as used herein, securing one element to another element caninclude direct securing and indirect securing. Additionally, as usedherein, “adjacent” does not necessarily denote contact. For example, oneelement can be adjacent another element without being in contact withthat element.

As used herein, the phrase “at least one of”, when used with a list ofitems, means different combinations of one or more of the listed itemsmay be used and only one of the items in the list may be needed. Theitem may be a particular object, thing, or category. In other words, “atleast one of” means any combination of items or number of items may beused from the list, but not all of the items in the list may berequired. For example, “at least one of item A, item B, and item C” maymean item A; item A and item B; item B; item A, item B, and item C; oritem B and item C. In some cases, “at least one of item A, item B, anditem C” may mean, for example, without limitation, two of item A, one ofitem B, and ten of item C; four of item B and seven of item C; or someother suitable combination.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to, e.g., a “second” item does notrequire or preclude the existence of, e.g., a “first” or lower-numbereditem, and/or, e.g., a “third” or higher-numbered item.

The schematic flow chart diagrams included herein are generally setforth as logical flow chart diagrams. As such, the depicted order andlabeled steps are indicative of one embodiment of the presented method.Other steps and methods may be conceived that are equivalent infunction, logic, or effect to one or more steps, or portions thereof, ofthe illustrated method. Additionally, the format and symbols employedare provided to explain the logical steps of the method and areunderstood not to limit the scope of the method. Although various arrowtypes and line types may be employed in the flow chart diagrams, theyare understood not to limit the scope of the corresponding method.Indeed, some arrows or other connectors may be used to indicate only thelogical flow of the method. For instance, an arrow may indicate awaiting or monitoring period of unspecified duration between enumeratedsteps of the depicted method. Additionally, the order in which aparticular method occurs may or may not strictly adhere to the order ofthe corresponding steps shown.

Embodiments of the system controller 140 may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,embodiments may take the form of a program product embodied in one ormore computer readable storage devices storing machine readable code,computer readable code, and/or program code, referred hereafter as code.The storage devices may be tangible, non-transitory, and/ornon-transmission. The storage devices may not embody signals. In acertain embodiment, the storage devices only employ signals foraccessing code.

The system controller 140 may be implemented as a hardware circuitcomprising custom VLSI circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. The system controller 140 may also be implemented inprogrammable hardware devices such as field programmable gate arrays,programmable array logic, programmable logic devices or the like.

The system controller 140 may also be implemented in code and/orsoftware for execution by various types of processors. An identifiedmodule of code may, for instance, comprise one or more physical orlogical blocks of executable code which may, for instance, be organizedas an object, procedure, or function. Nevertheless, the executables ofan identified module need not be physically located together, but maycomprise disparate instructions stored in different locations which,when joined logically together, comprise the module and achieve thestated purpose for the module.

Indeed, a module of code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different computer readable storage devices.Where a module or portions of a module are implemented in software, thesoftware portions are stored on one or more computer readable storagedevices.

Any combination of one or more computer readable medium may be utilizedby the system controller 140. The computer readable medium may be acomputer readable storage medium. The computer readable storage mediummay be a storage device storing the code. The storage device may be, forexample, but not limited to, an electronic, magnetic, optical,electromagnetic, infrared, holographic, micromechanical, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing.

More specific examples (a non-exhaustive list) of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(RAM), a read-only memory (ROM), an erasable programmable read-onlymemory (EPROM or Flash memory), a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing. In the context of this document,a computer readable storage medium may be any tangible medium that cancontain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may be written in anycombination of one or more programming languages including an objectoriented programming language such as Python, Ruby, Java, Smalltalk,C++, or the like, and conventional procedural programming languages,such as the “C” programming language, or the like, and/or machinelanguages such as assembly languages. The code may execute entirely onthe user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

The present subject matter may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. All changes which come within themeaning and range of equivalency of the claims are to be embraced withintheir scope.

What is claimed is:
 1. A thrust system for a vehicle, comprising: atleast four electrical power controllers; at least four electricalswitches each configured to receive electrical power from at least oneof the at least four electrical power controllers; and at least fourthrusters each configured to receive electrical power from at least oneof the at least four electrical switches; wherein the at least fourelectrical switches are operable to switch a supply of electrical powerfrom any of the at least four electrical power controllers to any one ofthe at least four thrusters.
 2. The system of claim 1, wherein the atleast four switches are operable to allow electrical power from the atleast four electrical power controllers to be concurrently supplied tothe at least four thrusters, with each electrical power controllersupplying power to a respective one of the at least four thrusters. 3.The system of claim 1, wherein one of the at least four electrical powercontrollers is a redundant power controller, and wherein in a first modea first of the at least four electrical power controllers supplieselectrical power to a first of the at least four thrusters, a second ofthe at least four electrical power controllers supplies electrical powerto a second of the at least four thrusters, and the redundant powercontroller supplies no electrical power to the first and secondthrusters, and wherein in a second mode one of the first and secondelectrical power controllers supplies no electrical power to the firstand second thrusters, respectively, and the redundant power controlsupplies electrical power to one of the first and second electricalpower controllers.
 4. The system of claim 1, wherein the at least fourelectrical switches are operable to allow electrical power from the atleast four electrical power controllers to be concurrently supplied tothe at least four thrusters, with each electrical power controllersupplying power to a respective one of the at least four thrusters. 5.The system of claim 1, wherein: each electrical power controllercomprises a first power output; each electrical switch comprises a firstpower input, a second power input, a first power output, and a secondpower output; the first power output of a first of the electrical powercontrollers is electrically coupled to the first power input of a firstof the electrical switches; the first power output of a second of theelectrical power controllers is electrically coupled to the second powerinput of the first of the electrical switches; the first power output ofa third of the electrical power controllers is electrically coupled tothe first power input of a second of the electrical switches; and thefirst power output of a fourth of the electrical power controllers iselectrically coupled to the second power input of the second of theelectrical switches.
 6. The system of claim 5, wherein: the first poweroutput of the first of the electrical switches is electrically coupledto the first power input of a third of the electrical switches; thesecond power output of the first of the electrical switches iselectrically coupled to the first power input of a fourth of theelectrical switches; the first power output of the second of theelectrical switches is electrically coupled to the second power input ofthe third of the electrical switches; the second power output of thesecond of the electrical switches is electrically coupled to the secondpower input of the fourth of the electrical switches; the first poweroutput of the third of the electrical switches is electrically coupledto a first of the thrusters, and the second power output of the third ofthe electrical switches is electrically coupled to a second of thethrusters; and the first power output of the fourth of the electricalswitches is electrically coupled to a third of the thrusters, and thesecond power output of the fourth of the electrical switches iselectrically coupled to a fourth of the thrusters.
 7. The system ofclaim 6, wherein: the first of the electrical switches is actuatable toeither (i) route electrical power from the first power input of thefirst of the electrical switches to the first power output of the firstof the electrical switches and route electrical power from the secondpower input of the first of the electrical switches to the second poweroutput of the first of the electrical switches, or (ii) route electricalpower from the first power input of the first of the electrical switchesto the second power output of the first of the electrical switches androute electrical power from the second power input of the first of theelectrical switches to the first power output of the first of theelectrical switches; the second of the electrical switches is actuatableto either (i) route electrical power from the first power input of thesecond of the electrical switches to the first power output of thesecond of the electrical switches and route electrical power from thesecond power input of the second of the electrical switches to thesecond power output of the second of the electrical switches, or (ii)route electrical power from the first power input of the second of theelectrical switches to the second power output of the second of theelectrical switches and route electrical power from the second powerinput of the second of the electrical switches to the first power outputof the second of the electrical switches; the third of the electricalswitches is actuatable to either (i) route electrical power from thefirst power input of the third of the electrical switches to the firstpower output of the third of the electrical switches and routeelectrical power from the second power input of the third of theelectrical switches to the second power output of the third of theelectrical switches, or (ii) route electrical power from the first powerinput of the third of the electrical switches to the second power outputof the third of the electrical switches and route electrical power fromthe second power input of the third of the electrical switches to thefirst power output of the third of the electrical switches; and thefourth of the electrical switches is actuatable to either (i) routeelectrical power from the first power input of the fourth of theelectrical switches to the first power output of the fourth of theelectrical switches and route electrical power from the second powerinput of the fourth of the electrical switches to the second poweroutput of the fourth of the electrical switches, or (ii) routeelectrical power from the first power input of the fourth of theelectrical switches to the second power output of the fourth of theelectrical switches and route electrical power from the second powerinput of the fourth of the electrical switches to the first power outputof the fourth of the electrical switches.
 8. The system of claim 1,wherein each of the at least four thrusters is an ion propulsionthruster.
 9. The system of claim 1, wherein each of the at least fourthrusters is enabled for maximum thrust output.
 10. The system of claim1, wherein the at least four electrical switches are configured suchthat each of the at least four electrical power controllers supplieselectrical power to only one of the at least four thrusters at a time.11. A thrust system for a vehicle, comprising: at least four electricalpower controllers; at least four electrical switches in power receivingcommunication with at least one of the electrical power controllers; atleast four thrusters each in power receiving communication with one ofthe electrical switches; and a system controller operably coupled to theelectrical switches and thrusters to control electrical power supplyfrom the electrical power controllers to the thrusters, wherein in afirst mode the system controller operates the electrical switches andthrusters to nonconcurrently supply power to each of the four thrustersfrom less than four electrical power controllers, and in a second modethe system controller operates the electrical switches and thrusters toconcurrently supply power to each of the four thrusters from arespective one of the four electrical power controllers.
 12. The thrustsystem of claim 11, wherein in a third mode the system controlleroperates the at least four electrical switches and the at least fourthrusters to nonconcurrently supply power to each of the at least fourthrusters from a dedicated one of each of the at least four electricalpower controllers.
 13. A method for providing thrust for a vehicle,comprising: supplying electrical power from any of at least fourelectrical power controllers; and routing electrical power from any ofthe at least four electrical power controllers to any of at least fourthrusters via at least four electrical switches.
 14. The method of claim13, wherein at least a second of the at least four electrical powercontrollers does not supply electrical power, the method furthercomprising: stopping the supply of electrical power from at least afirst of the at least four electrical power controllers; supplyingelectrical power from the at least second of the at least fourelectrical power controllers; and routing electrical power from the atleast second of the at least four electrical power controllers to any ofthe at least four thrusters via the at least four electrical switches.15. The method of claim 13, further comprising: supplying electricalpower from each of the at least four electrical power controllers; andconcurrently routing electrical power from the at least four electricalpower controllers to a respective one of each of four of the at leastfour thrusters.
 16. The method of claim 15, wherein the vehicle is asatellite, and wherein electrical power from each of the at least fourelectrical power controllers is supplied and electrical power from theat least four electrical power controllers is concurrently routed to arespective one of each of four of the at least four thrusters during atransfer orbit operation of the satellite.
 17. The thrust system ofclaim 1, wherein: each of the at least four electrical switches isconfigured to receive electrical power from two of the at least fourelectrical power controllers; and at least one of the at least fourelectrical switches comprises an output electrically connected with aninput of another of the at least four electrical switches to provideelectrical power to the other of the at least four electrical switches.18. The thrust system of claim 1, wherein: each of the at least fourelectrical switches is configured to receive electrical power from twoof the at least four electrical power controllers; and at least a thirdelectrical switch of the at least four electrical switches comprises: afirst output electrically connected with an input of a first electricalswitch of the at least four electrical switches to provide electricalpower to the first electrical switch of the at least four electricalswitches; and a second output electrically connected with an input of asecond electrical switch of the at least four electrical switches toprovide electrical power to the second electrical switch of the at leastfour electrical switches.
 19. The thrust system of claim 11, wherein ina third mode the system controller operates the at least four electricalswitches and the at least four thrusters to nonconcurrently supply powerto each of the at least four thrusters from less than four of the atleast four electrical power controllers, wherein one of the at leastfour electrical power controllers supplying power to the at least fourthrusters in the third mode does not supply power to the thrusters inthe first mode.
 20. The thrust system of claim 11, wherein the vehiclecomprises a satellite, the thrust system further comprising thesatellite.